Large-scale pumping of groundwater has caused large drawdowns – long-term drops in groundwater levels – in the Lower Fox River Valley , southeastern Wisconsin and Dane County . Drawdowns can cause serious economic, health and environmental problems: wells run dry and must be drilled deeper; concentrations of arsenic, radium, salts and other naturally occurring substances can reach unhealthy levels; and streams, lakes and wetlands lose water or dry up, depriving fish, birds, amphibians and mammals of vital habitat.